This invention relates to adjuvants for use in a pesticide formulation, and in particular to an environmentally compatible adjuvant composition prepared from acidulated soap stock.
It has long been common for farmers, homeowners, etc., to utilize pesticides to control the undesired proliferation of weeds, insects, rodents, and the like. Among the pesticides most commonly encountered are herbicides, which are used to destroy or inhibit undesired plant growth, and insecticides, which are used to destroy or repel insects.
As a result of efforts to clean up the environment, and in furtherance of ongoing efforts to minimize the future introduction of environmental contaminants into the soil, air and water, the use of pesticides has come under increased scrutiny in recent years. Numerous efforts have been made to reduce the toxicity and other harmful effects of pesticides on the environment, and at the same time to maintain or even improve the efficacy of the pesticides.
An adjuvant is a substance that is present in a pesticide formulation, or added to a pesticide formulation, to increase the efficacy of the pesticide or to improve the application characteristics of the pesticide. At the present time, adjuvants are typically made from petroleum based oils. Adjuvants are presently in widespread use in agriculture to increase the efficacy of various pesticides, including post-emergent herbicides. Post-emergent herbicides are herbicides that are applied after the germination of the crops and their appearance above the ground, and generally after the appearance of unwanted vegetation.
When used with post-emergent herbicides, adjuvants may act in many different ways to improve the efficacy of the herbicide. For example, adjuvants have commonly been used to improve the "wetting" of drops during spraying, to alter the volatility of the spray mixture, to improve the rain-fastness of the herbicide on the plant, to improve the penetration of the herbicide active ingredient (AI) into the target plant, to regulate the pH of the spray mix, to improve the distribution of the AI over the plant, to improve the compatibility of various crop protection agents in the mix tank and to reduce drift during spraying. Each of the beneficial characteristics of adjuvants acts in some manner to improve the effectiveness of the herbicide. As a result, the amount of herbicide that is applied for crop protection may be reduced in many cases, without a concomitant loss in efficacy of the herbicide.
Several general classifications of adjuvant materials in use with herbicides are known. As stated in a report by Colin A. Houston & Associates, Inc., titled, "Industrial Applications of Surfactants, North American Forecast to 1995" March 1987, which report is incorporated herein by reference, these classifications include activator adjuvants, spray modifier adjuvants, and utility modifier adjuvants. The classifications are further described below.
Activator adjuvants function to increase the apparent biological activity of the herbicides beyond the activity of that obtained by the herbicide alone. Within this classification are surfactants, crop oils, and crop oil concentrates. Surfactants improve the emulsifying, dispersing, spreading, and/or wetting characteristics of the spray mixture. Crop oils are nonphytotoxic mineral or vegetable oils which contain 1-2% surfactants and function in a manner similar to surfactants. Crop oil concentrates consist of mineral or vegetable oils with 17-20% added surfactant. These materials aid in penetration through the plant cuticle, and in reducing the surface tension of the spray droplets (wetting ability).
Spray modifier adjuvants modify the spray solution in a specified manner. This modification occurs either in the tank, in transit to the target, or in the target itself. Spray modifier adjuvants include spreaders, stickers, spreader-stickers, foaming agents, and thickeners. Spreaders function to increase the area of the spray droplets on the target substrate. Stickers function to adhere the spray droplets to the target surface, and increase the rain-fastness of the droplets. Spreader-stickers combine the functions of spreaders and stickers as described above. Foaming agents increase the surface area of air-filled liquid spray droplets. Thickeners function to increase the viscosity of the spray mixture, and to reduce the spray drift.
Utility modifier adjuvants function to broaden the range of conditions under which a given herbicide formulation may be used for maximum results. Specific utility modifier adjuvants include anti-foam agents, compatibility agents, and buffering agents. Anti-foam agents decrease and/or prevent foaming when the solution containing the herbicide formulation is agitated or sprayed. Compatibility agents function to allow and maintain an emulsification of two or more ingredients that would otherwise separate when mixed. Buffering agents function to moderate the pH of the water in the tank solution.
Agricultural adjuvants that are used with post-emergent herbicides are generally a blend of compounds comprising a surfactant (usually nonionic), as well as other active and inert ingredients. These adjuvants are commonly manufactured from petroleum-based oils and surfactants. The current trend toward more environmentally responsible agricultural chemicals creates a need for adjuvant products that are less harmful to the environment than prior art adjuvants, and that will allow greater herbicide efficacy at lower dosage rates.
Due to the aforementioned environmental concerns, as well the ever-present desire to provide the most effective product at the least overall cost, certain shortcomings have persisted in the art arising from the use of existing adjuvants in combination with conventional herbicides. For example, the prior art adjuvants do not provide the degree of penetration into the target substrate that is desired. A greater penetration into the substrate provides for greater efficacy, and thus allows the use of a smaller dosage of herbicide in order to obtain comparable visual injury to the substrate when compared to that obtained with larger doses of conventional adjuvants.
In addition, the targeted plant's metabolic defenses are often able to provide some degree of protection to the plant from the herbicide's active ingredient, thus limiting the efficacy of the herbicide. Due to the action of the plant's metabolic defenses against the herbicide, it is generally necessary to use a larger dose of the pesticide active ingredient than would be necessary if the metabolic defenses were not able to provide this protection to the plant.
It is desired to provide an adjuvant composition that enhances the efficacy of the pesticide. It is similarly desired to provide an adjuvant composition that allows greater penetration of the media into the target substrate. It is further desired to improve the protection of the herbicide's active ingredient against the plant's metabolic defenses by providing an adjuvant composition that allows more of the herbicide's active ingredient to reach the targeted areas of the substrate. Additionally, it is desired to provide an adjuvant composition that is less harmful to the environment than prior art adjuvants, and that enables a reduction to be made in the amount of the active ingredient that is applied to the substrate, and thus released into the environment.